#include <iostream>
#include <fstream>

using namespace std;

int main () {

ifstream in ("fact.in");
ofstream out ("fact.out");

int n, i, count ,temp;

in >> n;
count = 0;
int fives = 0;
int pivot = 1;
for (i = 1; count < n; i++)
{
	count ++;
	if (i % pivot == 0 )
		count += fives;
	if (i == pivot * 5)
	{
		pivot = i;
		fives ++;
		count ++;
	}
	if (count == n)
	{
		out << i*5;
		break;
	}
}
if (n == 0)
	out << 1;
else
	if (count > n)
		out << -1;
	
return 0;
}